Process of distilling wood.



R. STROBACH.

PROCESS OF DISTILLING WOOD.

APPLICATION FILED MAY 16, 1908.

Patented Jan; 23, 1912.

2 SHEETS-SHEET 1.

R. STROBAGH.

PROCESS OF DISTILLING WOOD.

APPLICATION FILED MAY 16, 1908.

1,015,5 19. Patented Jan. 23, 1912.

2 SHEETS-SHEET 2.

Fig. 2.

W///////// ////A i x 4 {-11 E) (i I @zwzf I UNITE STATES PATENT OFFICE.

BUDOLF STROB ACH, OFIPRAGUE-ZIZKOW,- AUSTRIA-HUNGARY.

PROCESS OF DISTILLING WOOD.

Specification of Letters Patent.-

Patented Jan. 23,1912.

To all whom it may concern:

Be it known that I, RUDOLF S'rRoBAcH, residing at Konigliche Weinberge,am Riegerpark 1472, Prague-Zizkow, Austria-Hungary, subject of theEmperor of Germany, have invented certain new and useful Improvements inand Relating to Processes for Distilling Wood, of which the following isa specification.

The invention relates to a process for extracting from the gases andvapors produced in the destructive distillation of wood and like organicmaterials, impurities and byproducts, such as tar, acetates, woodalcohol, etc. In such extraction and purification much difficulty hasheretofore been. experienced in removing and collecting the tarefficiently, conveniently and economically. In the most customary methodof extracting by-products, the tar and other condensable constituents ofthe gas or vapor are condensed in one operation, so producing a mixtureof tar and a complex liquid termed pyroligneoiis acid; the bulk of thetar is then permitted to settle out, the pyroligneous acid (stillcontaining some tar) is evaporated to free it from the remaining tar,and the vapors are treated in suitable apparatus to separate the aceticacid and wood-alcohol contained in it. The tar so obtained stillcontains'some .pyroligneous acid, and must be purified. As analternative to this process it has been proposed to accomplish theseparation of the tar by passing the gases or vapors produced bydestructive distillation, through a series of successive bathscomprising in the series mixtures in varying proportions of tar andacetic acid, and in so doing progressively reducing the temperature ofthe gases and vapors; these baths, however, being at so low temperaturesas to cause the acetic acid to be condensed and held back. Such methodhas numerous important disadvantages, among which are that the aceticacid must subsequently be separated from the tar by evaporation anddistillation as a separate operation and in special apparatus involvingthe application of further heat.

According to the present process the gases and vapors resulting from thedestructive distillation are passed through a single bath only of tar,and this tar bath is initially free from acid, and is maintained,initially and thereafter, at such a temperature that the acid in thegases and vapors is not retained by the tar, but passes on to beseparated thereafter; while the tar in such gases and vapors isretained, in an acid-freed con- "the gases or vapors resulting fromdestructive distillation, through a heated acid-freed tar bath ofregulated depth such that a single passage of the gases and vaporsthrough such bath results in the practically complete extraction of thetar carried by such gases and vapors, without the holding back of aceticacid and the like. This improved method has the important, advantagesthat not only is the tar so obtained substantially free from acid andtherefore in condition for immediate sale, but the other condensableby-products contained in the gases and vapors are not cooled to such a.point as to preclude their separation, one

after the other, in a single continuous operation and without theaddition of further heat either to the gases or vapors or to condensatestherefrom.

The object of the invention is to extract by-products from the gases andvapors produced by the destructive distillation of wood and like organicsubstances, in a more e'fiicient and economical manner and by acontinuous-process and to separate them, one

from another, during the extraction and without the addition of furtherheat to the gases or vapors or to the condensates obtained therefrom,and to obtain directly tar substantially free from acid, Wood alcohol,etc., and conversely, to obtain acetic acid or its acetate, woodalcohol, eta, substantially free vfrom tar;

In the accompanying drawings I illustrate an apparatus adapted forcarrying out the process as above described, and I will herein describethe process as carried out in the apparatus.

In said drawings: Figure 1 shows more or less diagrammatically a sideelevation and partial section of the apparatus, and Fig. 2 shows a topview of the apparatus.

In said drawings,-R designates a plurality of vertical retorts adaptedfor the destructive distillation of wood and like materials. There maybe as many of these retorts as desired; and there should be at least twosuch retorts, since according to my process, I- operate a plurality ofretorts simultaneously and charge them in alternation or rotation,mingling'together the gases or vapors evolved from the differentretorts, and conducting the charging in such manner that the mingledgases and vapors from the several retorts have a practically uniformcomposition; It will be understood that in the gases and vapors firstgiven off from a freshly charged retort, there is very little tar, andthatthe proportion of the tar .in the gases and vapors evolved fromtheretort increases as the distillation goes on. By charging the retorts inalternation or succession at proper intervals, and mingling the gasesand vapors from the several retorts before passing them to the purifyingapparatus, it is possible to maintain a practically uniform compositionof these gases and vapors; and this is very important for the successfulcarrying out of the present PIOCGSS.

The gases and vapors resulting from the destructive distillation areconducted from the several retorts R through pipes a into .a collectingtank or header S common to the series of retorts and are thence conveyedthrough a pipe 22 into a tar separator T, the

said pipe 6 extending to near the bottom of the tar separator and thereterminating in a cross-shaped distributer c the arms of which areprovided with a plurality of small perforations for the escape of thegases -"and vapors into themain portion of this separator. The tarseparator T is charged with tar before the operation begins. This tar isof sufiicient depth or thickness'above said distributer toextractpractically the whole quantity of tar contained in the smoke during thepassage thereof therethrough. A valved by-pass pipe I) is provided,connecting the header S with the main portion-of the tar separator T,whereby tar which collects in this header may be drawn off from time totime into the tar separator. In practice the tar'is not permitted tocollect in this header S to such extent that any material separation oftar from acetic acid and other by-products can take place in the header.

The gases and vapors from the retorts reach the tar separator at atemperature of from300 to 350 F., and, being distributed throughthe bathof tar by means of the distributer a, pass up through this bath of tarand, owing to the relatively great depth of this bath, practically allof the tar in such gases or vapors is held back, the remaining gases andvapors passing from the tar sepa-. rator throughthe pipe f or f; and byreason of the relatively high temperature at .60 ,which this tar bath ismaintained, both i'nitially and thereafter, the acetic acid, woodalcohol, and other condensable substances in the gases and vapors fromthe retorts are not held backor retained by the tar bath,

but pass onward through the pipe f or f These gases and vapors leave thetar separator at a temperature of about 240 to 250 F. I

' In the tar separator as well as in the re-' mainder of the apparatus,a partial vacuum is maintained by means .of' an injector J at the end ofthe apparatus, whereby a positive flow through the apparatus ismaintained. Owing to the depth of the tar bath in the tar separator T,the retorts R are operated under a pressure of usually from three tofive cm. of water.

From time to time, excess of tar in the separator Tis drawn off by meansof valved pipes 6 6 to a collecting tank E provided with an air valve dand draw off cock d; tar being drawn off from time to time in thismanner to maintain a nearly uniform depth of tar in the separator T.

The tar-freed gases escaping through the pipe F pass through one oranother of two receivers, K and K provided each with a cross-shapeddistributer g or. 9?.

In these The receivers are operated in alternation, for which reasonvalves v1 and 12 are provided in the pipes, f and f leading from the tarseparator to these receivers, and corresponding valves 12 and '0 areprovided in the pipes m and m leading from the receivers. The gases andvapors, in passing through the milkof lime solution in one or the otherof these receivers, part with their acetic acid, which-later combineswith the lime as acetate of lime. The receivers are operated. inalternation, one being emptied and recharged while the other isreceiving the gas. As soon as the contents of one receiver are found tobe neutralized by the acetic acid,

I absorbed therein, this receiver is put out of service and the gasesare passed through the other receiver. I

: The gases leaving the receiver K or K pass into a further receiver Kof similar construction and also containing milk of lime so1ution, inorder that any remaining acetic acid in the gas may be removed. Thisthird receiver K is connected with receiver.

K 'and K by valved pipes m wherebythe milk of lime in'receiver K may bedrawn off from time to time into one of the other receivers and replacedby fresh milk of lime.

The acid-freed gases from receiver K pass off through valved pipes Z andZ into one or another of two tanks L and L containing water and in whicha portion of the water contained" in the gases and vapors is condensed,and thenthe gases pass through pipe Z or Z, into one oranother of twodephlegmators D and Dtin which water still contained in the gases isextractedtherefrom to such extent that the wood alcohol to besubsequently condensed from thesegases will have a suitable degree ofconcentration. From these dephlegmators contained in the gases iscondensed and pipes X and X lead to coolers or condensers N and Nwherein the wood alcohol drawn ofi into tank's H and H; the gasesremaining which are in .the main fixed gases, being drawn off by meansof the injector J.

It will be observed that by the treatment described, and in theapparatus illustrated and described, the several valuable byproductscontained in the initially evolved gases and vapors, are each separatedsub,- stantially without admixture with another; that no heat isrequired to be added to any one of the several condensates in order toextract therefrom a substance which should not have been absorbedtherein but should have passed on into one of the later vessels of theapparatus to be there extracted; and that the operation is a continuousone.

What I claim is 1. The herein described process of obtaining acid-freetar and tar-free pyroligneous acid vapors from the gases and vaporsevolved during the destructive distillation of wood and like organicsubstances, which comprises passing said hot gases and vapors while at asuitable and substantially uniform temperaturethrough a suitable bath ofhot tar; and maintaining such a quantity of tar in said bath as willcause the condensation and extraction of substantially all of the tarfrom said hot gases and vapors, but which quantity of tar will be heatedto and maintained, solely by the heat of said gases and vapors, at atemperature which precludes the existence of condensed pyroligneous acidin said tar-bath.

' 2. The herein described process of obtaining acid-free tar andtar-free pyroligneous acid vapors from the gases and vapors evolvedduring the destructive distillation of wood and like organicsubstances,which comprises mingling the hot gases and vapors from a plurality ofretorts at different stages of distillation; passing said hot mingledgases and vapors through a suitable bath of hot tar; and maintainingsuch a quantity of tar in said bath as will cause the condensation andextraction of substantially allthe tar from said hot gases and vapors,but which quantity of tar will be heated to and maintained, solely bythe heat of said gases and vapors, at a temperature which pre-.

eludes the existence of condensed pyroligneous acid in said tar-bath.

3. The herein described process of separating constituents from the"gases and vapors evolved during the destructive distillatlon of woodand like organicsubstances,

which comprises passing said hot gasesand vapors through a suitable hottar-bath; maintaining such a quantity of-tar in said bath as will causethe condensation and extraction of substantially all of the tar fromsaid hot gases and vapors, but which quantity of tar will be maintainedby the heat of said gases and vapors 'at a temperature which precludesthe existence of condensed pyroligneous acid in said tar-bath; and thenseparately condensing and extracting the remaining condensableconstituents.

4. In the distillation of wood and like organic substances, a method ofseparating various constituents from the hot distillation gases andvapors, which comprises pass ing the same through a suitable bath maintained by said hot gases and vapors at a sufficient temperature to causethe extraction of substantially all of the tar therefrom, then passingthe remaining gases and vapors through a bath maintained thereby at atemperature sufficient to cause the extraction of substantially all ofthe acid vapors and then condensing the water'and the alcoholic vapors.

In witness whereof I have hereunto set my hand in presence of twowitnesses.

RUDOLF STROBAOH.

Witnesses:

J OHANNA GRUNOW, HARRY GUTH.

